Bobbin changing mechanism method and product

ABSTRACT

Coreless bobbins are loaded from a supply into an empty bobbin case and then automatically transferred into the bobbin holder and hook assembly of a conventional lockstitch sewing machine. Upon runout of the bobbin thread, and upon the signalling of such runout electrically, the empty bobbin case is automatically withdrawn from the holder and hook assembly for reloading and a new loaded bobbin case is automatically inserted into the holder and hook assembly of the sewing machine.

United States Patent [1 1 Mayer et al.

[ July 24, 1973 BOBBIN CHANGING MECHANISM METHOD AND PRODUCT [75]Inventors: Nathan Mayer, East Brunswick;

Stanley S. Lanes, Matawan, both of NJ.

[73] Assignee: Bobbin Monitor Corporation,

Jamesburg, NJ.

[22] Filed: Feb. 23, 1971 [21] Appl. N0.: 118,148

[52] 11.8. CI. 112/186 [51] Int. Cl D05b 59/04 [58] Field of Search112/186, 185, 180,

[56] References Cited UNITED STATES PATENTS Schumann et al. Dobner et al2/1956 Schuman et al. 112/180 2,507,470 5/1950 Hirsch 112/181 2,808,79510/1957 Wortham 112/186 X 3,376,838 4/1968 Schiffmacher et al 112/186FOREIGN PATENTS OR APPLICATIONS 908,215 10/1962 Great Britain 112/186Primary Examiner-H. Hampton Hunter Attorney-'-Amster & Rothstein [57]ABSTRACT Coreless bobbins are loaded from a supply into an empty bobbincase and then automatically transferred into the bobbin holder and hookassembly of a conventional lockstitch sewing machine. Upon runout of thebobbin thread, and upon the signalling of such runout electrically, theempty bobbin case is automatically withdrawn from the holder and hookassembly for reloading and a new loaded bobbin case is automaticallyinserted into the holder and hook assembly of the sewing machine.

15 Claims, 20 Drawing; Figures PAIENIEUJUL 24 ma 747, 547

SHEET I 1 [1F 5 BOBBIN CHANGING MECHANISM METHOD AND PRUINUCT Thepresent invention relates generally to methods and apparatus for theautomatic changeover of bobbins in sewing mechanisms, and in particularto an improved method for feeding bobbins to a sewing machine, anautomatic bobbin changing apparatus and improved components and productutilizable with such method and apparatus.

In the typical lockstitch sewing machine utilizing a bobbin thread woundupon a bobbin spool, the bobbin changing procedure involves the machineoperator in a number of sequential steps which usually include reachingunder the machine and removing the bobbin case containing the exhaustedor partially exhausted spool of bobbin thread, unlatching the spool fromthe case, removing the spool and replacing the same with a new spoolcontaining a full bobbin, reloading the bobbin case into the holder andhook assembly of the machine and thereafter re-establishing the stitchby the hand manipulation of the sewing machine causing the needle threadto engage the bobbin thread through the throat plate.

Particularly with the advent of present day sewing machines which arecapable of operating at stitching rates in the range of 5,000 to 6,000stitches per minute, the manual bobbin change sequence presents a numberof practical problems to the machine operator. Initially, in the absenceof an automatic changing mechanism, or at the very least of a bobbinrunout signalling system, the operator must be concerned with when thesupply of bobbin thread will be exhausted. This often results inoperator slowdown toward the end of the period in which the operatorfeels that the bobbin thread is about to be exhausted. Frequently, anoperator will discard partially exhausted bobbins and will reload thesewing machine prematurely or will completely exhaust the supply ofbobbin thread, with the necessity of then pulling back the work andrestitching. In many fabrics, pull-back and restitching causes therestitched length to have a patchy appearance; and indeed many fabricscannot tolerate the extra needle holes formed incident tothe needlepenetration without actual stitching due to the exhausted bobbin supplyand the resulting product becomes a reject. Further, there is apotential for the provision of a double stitch line if the operator isnot particularly careful in retracing his or her steps in the work.Still further, when utilizing a conventional bobbin containing bobbinthread wound on a reusable metal or throwaway type of spool, there is atendency for the bobbin spool to turn within the bobbin case which mayresult in tangling or fouling of the bobbin thread. This occurs mostfrequently when an operator has repetitive short runs (i.e. pockets) andis caused by the inertia of the bobbin in the bobbin case. In allevents, the bobbin change time is totally unproductive, usuallyrepresenting anywhere from 40 seconds to 60 seconds for the operator togo through the change se quence. Between the bobbin changing times,including the inherent operator slowdown when the operator believes thatthe bobbin thread is about to run out, the need for restitching and thepotential for fouling of the bobbin thread, there can be a substantialloss in operator productivity, particularly, if in response to bobbinthread run-out or tangling of the bobbin thread, the needle thread, andpossibly the needle as well, break.

Obviously, there exists a need for improved bobbin changing techniquesand methods for the vast number of lockstitch sewing machines which arein widespread use throughout the world. Although a variety of approacheshave been suggested to avoid the foregoing difficulties, to ourknowledge there has been no system or method evolved which as by asimple attachment to a conventional sewing machine and the provision ofan appropriate hand-operated or automated control, the machine operatoris automatically advised of the imminent runout of the bobbin thread,with the warning occurring sufficiently in advance of runout to enablethe operator to immediately stop sewing and by a simple manipulation,such as pushing a button or pressing a switch, is able to initiate abobbin changing cycle during which the empty bobbin case in the sewingmachine is automatically removed and replaced by a bobbin case loadedwith bobbin thread. Thereupon, the operator, without further adieu andwith minimum risk of bobbin thread fouling, loss of stitch or breakingof a needle or needle thread, is able to resume the stitching operation.

Broadly, it is an object of the present invention to provide improvedmechanisms and techniques obviating one or more of the foregoingdifficulties and achieving one or more of the foregoing objectives.Specifically, it is within the contemplation of the present invention toprovide a bobbin changing mechanism and method and related bobbinassembly and construction which facilitates automatic bobbin reloadinginitiated prior to bobbin thread runout; which enables the stitchingoperation to be discontinued prior to improper stitching; which providesa rapid and automatic bobbin changing cycle and the reestablishment ofthe stitching operation; and which accomplishes the foregoing withminimum risk of machine malfunction, operator fatigue and lostproductive time.

The bobbin changing method and apparatus of the present inventionemploys an improved bobbin assembly which comprises at least twotoroidal coreless wound bobbins disposed in leading and trailingrelation to each other and in axial alignment with each other.Preferably, each of the bobbins includesplural bobbin threadconvolutions packed to provide a toroidal body having a substantiallycylindrical outer peripheral wall adapted to conform to and fit snuglywithin the bobbin case and terminating at its opposite ends in leadingand trailing faces. The leading and trailing bobbins are interconnectedby an intermediate length of bobbin thread extending from the leadingface of one of the bobbins at its inner periphery, over its outerperipheral wall, over the outer wall of the trailing one of the bobbinsand then merging with the toroidal body thereof at its trailing face.Advantageously, this bobbin assembly can include a substantial number ofindividual bobbins disposed in axial alignment one behind the other forautomatic feed to the sewing machine such that the supply need not bereplenished more frequently than several (i.e. two or three) times a dayas compared to a typical sewing machine running on straight goods whichmay require as many as seven to 10 changeover-s an hour. 1

In accordance with method aspects of the present invention,woundcoreless bobbins are fed in succession in the required bobbin caseto the bobbin holder of a sewingmachine by forming a bobbin assembly ofthe foregoing type including at least two toroidal coreless andcheekless wound bobbins in leading and trailing relation to each other,loading the leading bobbin into the bobbin case by axially moving theleading bobbin away from the trailing bobbin and while still connectedthereto by an intermediate length of bobbin thread and then moving theloaded bobbin case from the location at which it is loaded into atransfer location in axial alignment with the bobbin holder, with theleading bobbin still connected to the trailing bobbin to draw out saidintermediate length of bobbin thread. Thereupon, the intermediate lengthof bobbin thread is severed at a point removed from the loaded bobbincase to leave a tail of bobbin thread on the leading bobbin. In thefinal step, the loaded bobbin case is moved into the bobbin holder withthe bobbin thread tail extending therefrom. In response to the firstneedle stroke, the bobbin thread tail is pulled under the tensioningspring of the bobbin case and guided into stitch-forming relation withthe needle thread, such that the sewing machine is capable of resumingits stitching function in its normal mode.

In accordance with apparatus aspects of the present invention, there isprovided an automatic bobbin changing mechanism for a sewing machine ofthe type which utilizes a bobbin case containing a wound bobbin andreceived within a bobbin holder for engagement of the bobbin thread by ahook rotating on a hook axis which mechanism comprises a support adaptedto be mounted on the sewing machine, for example, by replacing theconventional slide plate of the sewing machine. A carrier is mounted onthe support for rotation about a carrier axis extending parallel to andoffset from the hook axis, with the carrier including at least twobobbin case receivers at circumferentially spaced locations. Eachreceiver is adapted to receive a bobbin case for transfer between abobbin loading position at a removed location from the bobbin holder anda case transfer position at a confronting location in alignment with thebobbin holder. Bobbin loading means are provided at the removed locationwhich are adapted to receive a supply of coreless bobbins for feed oneat a time into empty bobbin cases presented successively in the bobbinloading position. Provision is made for turning the carrier to bring theloaded bobbin case into thecase transfer position at which time meansare operable to disengage the loaded bobbin case from its receiver andtransfer the same to the bobbin holder of the sewing machine. Sensingmeans are operable to detect the runout of the bobbin thread in theloaded bobbin case in the sewing machine and means are operable inresponse to the sensing means to disengage the empty bobbin case fromthe bobbin case holder and return the same to the receiver at the casetransfer position for movement to the bobbin loading position for thereloading of the empty bobbin case from the bobbin supply.

The above brief description, as well as further objects, features andadvantages of the present invention will be more fully appreciated byreference to the following detailed description of a presently preferredbut nonetheless illustrative embodiment in accordance with the presentinvention, when taken in conjunction with the accompanying drawings,wherein:

FIG. 1 is a plan view with parts broken away showing a typical sewingmachine including a bobbin feeding mechanism or attachment embodyingfeatures of the present invention;

FIG. 2 is a perspective and diagrammatic view showing the bobbinchanging mechanism in elemental form to facilitate an understanding ofthe invention, with the mechanism shown in the running mode of thesewing machine prior to a bobbin changing cycle;

FIG. 3 is a fragmentary view similar to FIG. 2 but showing the bobbinchanging mechanism in its case transfer phase, with the transfer memberbeing positioned to pick up the empty bobbin case in the conventionalbobbin case holder and hook assembly of the sewing machine; a

FIG. 4 is a fragmentary view similar to FIG. 3 but with the casetransfer phase advanced to the point where the empty case has beenwithdrawn from the bobbin case holder and reloaded into the carrier ofthe bobbin changing mechanism;

FIG. 5 is a diagramatic view similar to FIG. 4 but with the carrierhaving rotated through to bring the empty case into the bobbin loadingposition, and with the transfer phase advanced to the point wherein aloaded bobbin case has been engaged within the holder and hook assemblyof the sewing machine;

FIG. 6 is a simplified diagramatic and schematic showing of a bobbinthread runout detection system embodied in a simplified form of thepresent invention;

FIG. 7 is an elevational view, on an enlarged scale, of an improvedbobbin case employed in the present mechanism, shown from the closedbase wall end thereof;

FIG. 8 is a sectional view, partially taken along line 88 of FIG. 7 andshowing in full and dotted lines the transfer head employed with thebobbin case during the transfer phase of the bobbin changing cycle whichincludes a first sequence during which an empty bobbin case is withdrawnfrom the bobbin holder and a second sequence, after a loaded bobbin caseis brought into the case transfer position, during which the transferhead loads the bobbin case into the bobbin holder;

FIG. 9 is a bottom plan view of the improved bobbin case of the presentinvention taken on FIG. 8 and showing the bobbin case as held within thebobbin holder of a conventional sewing machine and with the bobbinthread emerging therefrom beneath the adjustable tension spring;

FIG. 10 is a diagramatic elevational view showing the stitching cyclestopped and at a point wherein the previous bobbin thread has run outand a new bobbin thread is in position beneath the sensing contactpreparatory to reestablishment of stitching;

FIG. 11 is a view similar to FIG. 10 at a later time in the stitchforming sequence;

FIG. 12 is a view similar to FIG. 11 but at a still further time in thestitching-forming sequence in which a stitch is substantially formedafter the start-up of the sewing machine following bobbin threadreplenishment;

FIG. 13 is a diagramatic and sectional view along a typical stitch lineillustrating the segment thereof which includes the overlapping portionsof bobbin thread resulting from runout of one bobbin, replenishment ofthe bobbin thread and pickup of stitching;

FIG. 14 is a sectional view, on an enlarged scale, taken substantiallyalong the line 14-14 of FIG. 1 and showing the details of a typicalbobbin changing mechanism embodying features of the present invention asmounted on a lockstitch sewing machine in operative relation to thebobbin case holder and hook assembly thereof;

FIG. shows an illustrative cam development for the main actuating cam ofthe bobbin changing mechanism;

FIG. 16 is a diagramatic showing of the cam development, stretched outfor convenience in illustration, and including progressive showings atvarious times in the bobbin changing cycle to assist in understandingthe present invention;

FIG. 17 is a sectional view taken substantially along the line 17-17 ofFIG. 14 and looking in the direction of the arrows showing the mechanismat a point in its cycle wherein a loaded bobbin case is waiting at thebobbin loading position removed from the case transfer position andduring the normal stitching mode of the sewing machine between thereloading of bobbins;

FIG. 18 is a view similar to FIG. 17 but showing the loaded bobbin caseas it approaches the case transfer position and with an empty bobbincase approaching the bobbin loading position, the carrier having rotatedcounterclockwise through something less than 180 from the positionillustrated in FIG. 17;

FIG. 19 is a sectional view taken substantially along the line 19-19 ofFIG. 14 and looking in the direction of the arrows; and,

FIG. 20 is a sectional view taken substantially along the line 20-20 ofFIG. 14 and looking in the direction of the arrows.

Referring now specifically to the drawings, and initially to FIG. 1,there is shown a typical lockstitch sewing machine, generally designatedby the reference numeral 30, which includes a machine table 32, bedplate 34 and machine body or head 36. The machine head 36 includes theusual main shaft which is driven at one end and is operative at theother or head end to actuate a needle bar (not shown) for reciprocatingneedle 38 (see FIG. 2) through its needle stroke in relation to thebobbin holder and hook assembly 40 which is mounted beneath the bedplate 34 and is rotated by hook shaft 42. The present bobbin changingmechanism, generally designated by the reference numeral 44, isconstructed for use with a wide variety of conventional sewing machinesof the type generally described herein and as exemplified by machinesmanufactured by Singer, Union Special, Brothers, Necchi, Pfaff and thelike, such machines capable of providing Federal Stitch No. 301,commonly called a lockstitch. Accordingly, further description of suchconventional sewing machines is deemed unnecessary for those skilled inthis art and for an understanding of the present invention.

In this illustrative embodiment, the bobbin changing mechanism 44 isillustrated and described in conjunction with a rather elementary manualactuating system including hand crank 46 (FIG. 1) and a highlysimplified runout signalling system (FIG. 6). However, it will beappreciated, as the description proceeds, that the present mechanism isparticulary suited to be completely automated in response to thesignalling of bobbin thread runout. In such a completely automatedversion, the change cycle will occur without operator intervention. Thesignalling system will disable the sewing machine during the bobbinchanging cycle and the cycle will go forward to remove an empty bobbincase from the bobbin holder and replace the same by a bobbin case havingloaded therein a new coreless bobbin, followed by the signalling of themachine operator that the machine has a replenished supply of bobbinthread and is conditioned for the next stitching interval at the end ofwhich the bobbin runout is again signalled and the bobbin changing cycleautomatically repeated by the automated controls.

An overall understanding of the invention can be had by progressivereference to FIGS. 2 to 5 inclusive and the following description of theelements of bobbin changing mechanism 44 and its bobbin changing cycle.In these simplified diagramatic views, the bobbin changing mechanism 44is seen to include a rotatable bobbin case the two 48 having opposedbobbin case receivers R1, R2 which move in succession from a casetransfer position in axial alignment with the bobbin holder and hookassembly 40 and the hook shaft 42 to a bobbin loading position at aremoved location. The mechanism 44 includes a case transfer mechanism 50which includes a transfer member 52 which is operable along the axialpath in'alignment with the hook axis between operative and retractivepositions relative to carrier 48 and the assembly 40. In theillustrative position of FIG. 2, the sewing machine is running and hasone of thetwo bobbin cases (X1) received within the holder and hookmechanism 40, with the other of the bobbin cases (X2) being supported onthe carrier 48 at the bobbin loading position and containing therein abobbin B2 which is fed into bobbin case X2 from the bobbin supplymagazine 54. Magazine 54 is mounted to be in axial alignment withsuccessive empty bobbin cases brought into the bobbin loading positionsuch that it can feed successive coreless bobbins, such as leadingbobbin B2, into the successively emptied bobbin cases X1, X2 which arebrought into this loading position. During the normal running mode ofthe sewing machine, the bobbin thread BTl emerging from bobbin B1 inbobbin case X1 is monitored by a corresponding contact S1 (see FIG. 6)in the illustrated and highly simplified signalling device 56 whichincludes energizing source 56a, main switch 56b, step-down transformer56c and indicator bulb 56d. The secondary of step-down transformer 60 isgrounded at 56c as is the particular bobbin case X1 at 56f such thatupon runout of the bobbin thread BTl, the operator is signalled by light56d to initiate the bobbin changing cycle by turnbase wallof the emptybobbin case Xl. Thereupon, the

transfer member 52 is turned to lock the transfer head within the bobbincase such that upon thereturn stroke thereof (compare FIGS. 3 and 4) theempty bobbin case X1 is retracted from the bobbin mechanisms 40 of thesewing machine and loaded into the aligned and previously empty receiverof the carrier (see FIG. 3). The transfer member 52 then is releasedfrom the transferred empty bobbin case X1 and moved to a clearanceposition relative to carrier 48 on the side thereof remote from thebobbin mechanism 40, as illustrated diagramatically and indicated by theseveral arrows on transfer member 52 in FIG. 4. Thereupon the carrier 48turns through (compare FIGS. 4 and 5) to bring empty bobbin case X1 intoalignment with the bobbin supply magazine 54 (see FIG. 5) and concurrently the loaded and waiting bobbin case X2 is moved to the casetransfer position. The FIG. 5 showing illustrates bobbin X2 alreadymoved from the case transfer position supported on carrier 48 by thenext forward stroke of transfer member 52 into the holder and hookassembly 40 of the sewing machine. The transfer member 52 then movesthrough its return stroke, as indicated by the directional arrow in FIG.2, into the retracted position relative to bobbin holder and hookassembly 40 and the bobbin changing apparatus 44 is once again in thestandby position shown diagramatically in FIG. 2. In such standbyposition, the sewing machine has been loaded and is running with a fullbobbin case X2; and the mechanism 44 has its empty receiver R2 alignedwith assembly 40, with the other bobbin case X1 waiting in the bobbinloading position for the next bobbin changing cycle.

With the foregoing general understanding of the overall mechanisms andsequence of operations during a typical bobbin changing cycle, referencewill now be made to the detail showing in the remaining figures for adescription of the specific construction of a typical bobbin changingmechanism which is preferably constructed to be mounted on the sewingmachine as an attachment which may be suspended from the machine byreplacing the slide plate thereof. As seen best in FIG. 14 and as isgenerally understood, in a conventional sewing machine, the bed plate 34includes a stationary throat plate 34a provided with the required feeddog slots (not shown) and needle hole 34b through which needle 38reciprocates during the normal operation of the sewing machine. Ratherthan the conventional sewing machine slide plate, there is provided acombined slide and mounting plate 60 which is received within a slideplate guideway 340 (see FIGS. 17 to 20) such that slide plate 60 may bemoved toward and away from throat plate 340, as may be required fromtime to time in the servicing of the sewing machine. Slide plate 60 maybe locked into position on the bed plate 34 of the sewing machine in anyconvenient fashion, as by the provision of one or more mounting screws62 (see FIG. 20) which extend through top mounting plate 64 and aretapped into the lock plate or bar 66, which is drawn up against theunderside of the feed bed 34 upon tightening of the mounting screws 62.Top plate 64 is part of a frame or chassis 68 which includes spaced andparallel front and rear mounting plates 70, 72 connected by a bottomplate 74. The front mounting plate 70 is spaced in relation to thebobbin holder and hook mechanism 40 to provide adequate space for thecarrier or bobbin changing carrier or shuttle 48 which is journalled forrotation about a hori zontal carrier axis which is offset from, spacedbelow and parallel to the axis of hook shaft 42. In this illustrativeembodiment, the mechanism or attachment 44 includes a main shaft 76which is appropriately journalled on the back mounting plate 72 and hasattached thereto the main actuating cam 78 which in the form of a barrelcam extending from the back mounting plate 72 through the central cutout70a in the front mounting plate 70 which is also provided with anenlarged well 70b. The main actuating cam 78 is provided with an axialand integral hub 80 extending beyond plate 70 on which hub the carrier48 is journalled. The carrier is held on hub 80 in any convenientfashion, such as by lock washer 82 and nut 84. Thus, both the carrier 48and the main cam 78 are capable of turning on the common axis affordedby shaft 76. The carrier 48 and main cam 70 thus are mounted forrotation relative to each other and for movement in unison (when carrier48 is coupled to the main actuating cam 78) as will be subsequentlydescribed. This construction is necessary in this illustrativeembodiment since the bobbin changing mechanism 44 is designed with anoperating cycle in which main cam 78 rotates through 360 and carrier 48rotates only during approximately 180 of cam rotation.

The mechanism 44 is actuated via the main cam 78 through the provisionof a main driving sprocket 86 which is pinned to shaft 76 and isconnected via chain 88 to the actuating sprocket 90 (see FIG. 1) whichis on actuating shaft 92 carrying hand crank 46. Thus, in response toturning of hand crank 46, main shaft 76 rotates the barrel cam 78 toinitiate and complete a bobbin changing cycle. Provision may be made inthe manual actuating mechanism to permit the turning of shaft 76 only inthe particular direction for which the mechanism 44 is designed; andappropriate detents, etc. may be provided such that the manual drive isdecoupled at the end of a bobbin changing cycle to avoid a situationwherein the operator inadvertently goes beyond the requisite 360 ofrotation to the main cam 78. Also, as previously indicated, this simplemanual actuating mechanism may be replaced by an automated control inwhich an appropriate fractional horsepower motor would be mounteddirectly on shaft 76 (at the location of drive pulley 86), with themotor being connected in an appropriate motor control including thebobbin runout sensors (see FIG. 6).

In this illustrative embodiment, which is constructed to employ twobobbin cases, each of which is successively loaded with a coreless andcheekless bobbin (i.e. B1, B2), there are provided two bobbin receiversor seats R1, R2 circumferentially spaced at 180 relative to each otheron carrier 48. The receivers are of identical construction and areconstructed to snugly receive and support the bobbin cases for movementfrom the bobbin loading position removed from the hook axis to the casetransfer position along that axis and to permit operation of thetransfer mechanism 50 including the transfer member 52. Since the bobbinreceivers R1, R2 are constructed to receive somewhat modified bobbincases X1, X2, it will be useful to first described the modified bobbincase, seen best in FIGS. 7 to 9 inclusive. In the modified bobbin caseconstruction suitable for both cases X1 and X2, bobbin case 94 has acupshaped bobbin case body 96 which includes a cylindrical body wall 98terminating at one end in a case opening 100 through which the bobbin Bis loaded and terminated and closed at the other end in a base wall 102which is curved in the usual fashion. In the curved base wall 102contiguous with its junction with the adjacent end of the cylindricalbody wall 96 and at the 12 oclock position on the bobbin case 94, thereis provided the usual needle hole 104. Rather than providing the bobbinthread tensioning spring at approximately the 11 oclock position, as isconventional, the modified bobbin case 94 is provided with a bobbinthread tensioning and guiding mechanism at a diametrically opposedlocation corresponding approximately to 6 o" clock. This mechanismincludes a V-shape cut 106 (see FIG. 9) in the cylindrical body wall 98which extends inwardly from case opening 100 and terminates at its apexin a throat 108 through which the bobbin thread emerges (see FIGS. 7 and8). The contiguous portion of the curved base wall 102 is provided witha radial guideway 110 in the same plane as the throat 108 through whichthe bobbin thread is guided between base wall 102 and the adjacentsensor or contact S. The bobbin thread tensioning and guiding mechanismis completed by the provision of tensioning spring 112 having the usualadjustment screw 114. As described in copending application Ser. No.136,706, filed Apr. 23, 1971, entitled Bobbin Runout Signalling Device,the emergence of the bobbin thread BT at the 6 oclock location and at apoint substantially removed from the needle hole 104 and the coactingsensor S provides a bobbin runout signal with a reasonable length ofbobbin thread remaining and available for continued stitching until theoperator (or an automatic control) is capable of responding to thebobbin runout signal to discontinue the stitching operation. Thus thereis the reasonable assurance that the stitching operation will bediscontinued without interrupting the continuity of the stitch, asillustrated in FIG. 10, and enabling the stitch to be resumed asprogressively illustrated in FIGS. 1 1 to 13, with the remainder btl ofthe exhausted bobbin thread BTl captured in the stitch line as thestitching operation is resumed with the replenished bobbin thread BT2.It will be appreciated that the FIG. 13 showing is on a greatlyexaggerated scale and that in the typical stitched assembly, there willbe very little tell-tale trace along the stitch line length whereinthere is an overlap of bobbin threads at the underside of the stitchedassembly. Of course, any tell-tale presence of the bobbin thread, suchas the beginning bt2 of the next bobbin shown in FIG. 13 can be trimmed.As may also be appreciated from inspecting FIGS. 11 and 12, thebeginning bt2 of the replenishing bobbin thread BT2 is automaticallyengaged beneath the sensor at the commencement of the stitchingoperation and interengaged with the needle thread NT at the time thestitching operation is resumed.

Continuing with the description of the modified bobbin case 94, it wouldbe appreciated that the usual bobbin spool keeper mounted on thecurvedbase wall 102 is eliminated and this wall is constructed with asimple keyhole shaped slot 116 through which the head of the transfermember 52 is inserted for withdrawing the empty bobbin case" from thebobbin holder, as illustrated diagramatically in FIGS. 3 and 16 and aswillbe more fully described. Finally, the bobbin case 94 is provided onthe cylindrical body wall 98 with diametrically opposed guideways 118,120 which extend lengthwise of wall 98, are arranged at the 3 oclock and9 oclock positions respectively and are adapted to receive correspondingholding springs provided in the bobbin receivers R1, R2 of the carrieror shuttle 48 and also in the bobbin holding and hook mechanism 40.

Now to a description of the identical bobbin case receivers R1, R2, asseen best in FIGS. l4, l6 and 17, receiver R1 includes a circular seat122 which is of a depth corresponding substantially to the depth ofcylindrical body wall 98 and of a diameter to snugly accommodate bobbincase 94. The bottom of the seat 122 is relieved away, as indicated at124, to provide a curved shoulder against which an annular segment ofthe curved base wall 102 rests. The curved shoulder 124 terminates inthrough opening 126 to the backside of the carrier 48. Opening 126provides the necessary clearance for the transfer member 52 to passduring the forward and return strokes thereof when an empty bobbin caseis removed from the assembly 40 and the transfer member moves to theclearance position illustrated in FIG. 4 and when the transfer headmoves through its forward stroke to push a reloaded bobbin case backinto the assembly 40 as illustrated in FIG. 5. The construction of therespective bobbin case receivers R1, R2 is completed by the provision ofdiametrically opposed springs 128, 130 which are engaged respectively inthe guide ways or slots 118, and extend lengthwise of circular seat 122.Appropriate clearances are provided behind the respective springs 128,such that they may function to engage the bobbin case at the 3 oclockand 9 oclock positions, both in the bobbin loading position asexemplified by the loaded bobbin case X2 in FIG. 17 and during movementto the case transfer position as substantially. shown in FIG. 18.

Based upon an understanding of the modified bobbin case and the mannerin which it is held in carrier 48, it will be appreciated that theotherwise conventional bobbin holder and hook assembly 40 of theconventional machine must also be modified. As seen best in FIG. 14 andin the severalprogressive showings of FIG. 16, assembly 40 includes aconventional revolving hook 40a which rotates with hook shaft 42 and isprovided with raceway 40b which receives a modified bobbin holder 40cheld stationary by the conventional keeper 40d and provided withdiametrically opposed spring fingers 128, 130 received respectively inbobbin case guide ways 118', 120'. This arrangement holds the bobbincase 94 in a stationary position relative to the bobbin holder 400, withthis subassembly being held stationary as bobbin hook 40a rotates undercontrol of book shaft 42 in the conventionallmanner to interengage theneedle thread NT and the bobbin thread ET in the usual fashion, as showndiagramatically in FIGS. 10 to 12 inclusive.

As seen best in FIG. 14, the bobbin supply magazine 54 is stationary andincludes an elongated and cylindrical magazine body 54a which terminatesat one end in an exit opening 54b coextensive and in axial alignmentwith the successive receivers R1, R2 which are brought into the bobbinloading position and is closed at its opposite end by a base wall 54c.The magazine 54 is removably mounted to extend with its axis parallel toand spaced from the axis of the hook shaft 42 on a mounting bracket 132on thebottom plate 74 of the frame 68. The magazine 54 contains theplurality of toroidal coreless wound bobbins disposed one behind theother and in axial alignment witheach other, with the successive bobbinsin the magazine being designated as B3, B4, B5, etc. Each of the bobbinsis of identical construction. Representative bobbin, designated bythenumere] 134, is seen to include plural bobbin thread convolutionspacked to provide a toroidal body 134a having a substantiallycylindrical outer peripheral wall terminating at one end in a leadingface 134!) which is curved to conform generally to the curved base wall102 of the bobbin case 94 and at its opposite end in a planar trailingface 134a. Each of the bobbins is interconnected by a continuation ofthe bobbin thread of the leading one of the bobbins which emerges fromthe inner periphery thereof at its leading face (i.e. face 1314b),extends over its outer peripheral wall and the outer peripheral wall ofthe next adjacent and trailing bobbin and merges with the toroidal bodyof the trailing bobbin at its trailing face. The thread continuationbetween leading bobbin B2 and trailing bobbin B3 is representative anddesignated by the reference numeral 136. Successive continuations (i.e.continuation 136) will provide the requisite bobbin tails betweensuccessive bobbins fed into the sewing machine (i.e. tail bt2 in FIGS.to 12). Behind the stack of bobbins within magazine body 54a, there isdisposed a spring 138 which is seated against base wall 54c andcontinuously urges successive leading bobbins into the empty bobbincases 94 in the receivers R1, R2 which are successively presented at thebobbin loading position in response to each 180 index of the carrier 48.

Reference will now be made to FIGS. 14 to 16 inclusive for a descriptionof the bobbin case transfer mechanism 50 which is operable duringapproximately the first 90 of rotation of the main actuating cam 78 towithdraw the empty bobbin case from the bobbin holding and hook assembly40 and during approximately the last 90 of the bobbin changing cycle toload the next full bobbin case into the assembly 40 and to thereafterretract for running of the sewing machine. The case transfer mechanism50 includes the transfer member 52 which includes an elongatedcylindrical body 52a which is mounted for axial sliding movement inalignment with hook shaft 42 on the front and back mounting plate 70,72. Toward its trailing end, body 52a is provided with an elongatedfollower keyway 52b which receives cam pin 52c on back plate 72.Follower keyway 52b and cam pin 52c cooperate to rock transfer member 52through a limited angle at the forward limit of its axial reciprocationto lock the same to an empty bobbin case for its withdrawal fromassembly 40 as will be described. Intermediate its ends, the transfermember body 520 carries a cam follower head 52d which is supportedbetween collars 52e, 52f fixed to the body and extends into the camtrack 78a on main cam 78. Follower head 52d is held against rotation byalso slidably mounting the same on slide pin 521 (see FIG. 20) on frame68. Projecting from the forward end of body 52a is mounting stern 52gwhich at its leading end carries a traverse case engaging pin 52h whichis dimensioned to fit through keyhole slot 1 16 in the bobbin case (seeFIG. 7) and to be locked within the case upon rocking of member 52 (seeFIG. 8). Behind pin 52h is a case pusher head 52i which has a concavelycurved front face adapted to engage and bear against the outer surfaceof the curved base wall 102 of the bobbin case 94 during the forwardcase inserting stroke of member 52 (see FIG. 8). Head 52i is mounted onstem 52g with a back-up spring 52j therebehind which provides aresilient cushioning mount for head 52i.

Reference will now be made to the illustrative cam development of FIG.15 and to the diagramatic showing of FIG. 16 for an explanation of thefunction of the bobbin case transfer mechanism 50 which is functionalduring the beginning and end of a bobbin changing cycle of the machine.During the normal running of the sewing machine, the transfer mechanism50 is in the standby position A (corresponding to FIGS. 2 and 14), withmember 52 retracted and in a rotational attitude such that thetransverse pickup pin 52h is oriented to enter the keyway slot 116 inbobbin case 94.

The rise portion of cam track 78a between positions A and B (FIG. 15) issuch as to advance the transfer member 52 through a forward stroke tothe bobbin case pickup position B (corresponding to FIG. 3); and afterpickup pin 52h enters the bobbin case, it is rotated due to the cammingaction of pin 520 in cam slot 52b to lock pin 52h within the bobbin case94 against the inner surface of base wall 102. The cam development oftrack 78a between position B and position C (see FIG. 15) is such as tocause the transfer member 52 to move through its retracting stroke, withthe coacting pin 52c and cam slot 52b at the opposite extremity beingarranged to rotate member 52 to disengage pin 52h from bobbin case 94after the latter is seated in receiver R1 of carrier 48. Thereupon, thepin 52h is aligned relative to slot 116 and may be disengaged therefromsuch that the transfer member 52 may be retracted relative to the bobbincase and moved to the clearance position C. During the next 180 ofrotation of main cam 78, cam follower 52d is in the dwell portion of camtrack 78a during which time carrier 48 is rotated through 180 to bringreceiver R2 into a bobbin case transfer position (not shown butcorresponding generally to the FIG. 18 position). Thereupon, the riseportion of the cam track 78a between position D and position E is suchas to advance the transfer member 52 from the retracted clearanceposition C through its forward stroke. During the first portion of theforward stroke, the pusher head 52i engages the exterior of base wall102 to thrust the loaded bobbin case X2 forwardly from receiver R2 andinto the empty bobbin holder, with the forward position of pusher head52i corresponding to the case loading position E. It is to be noted thatin such case loading position, the degree of forward movement of thetransfer member 52 is somewhat less than that in the case pickupposition B since it is not necessary for the pickup pin 52h to enter thebobbin case during the case loading stroke. The final cam developmentbetween position E and position A is such as to return the transfermember 52 to the standby position for the normal running mode of thesewing machine While the transfer mechanism 50 is in the retractedclearance position commencing at position C on the cam development andfor the next 180 of the cam rotation, it is inactive and the transfermechanism 50 is clear of the carrier 48. At this point, the carrier hasan empty bobbin case in one receiver (i.e. receiver R1) and a loadedbobbin case in the other receiver (i.e. receiver R2). During this second180 of cam rotation, provision is made for coupling carrier 48 to maincam 78 to index carrier through 180' to bring the empty bobbin case tothe bobbin loading position removed from the bobbin holder and hookassembly 40 and to bring the loaded bobbin case to that position forreloading of the sewing machine. Coupling of the main actuating cam 78to the carrier 48 is accomplished by the cam operated couplingmechanism, seen best. in FIGS. 14, 19 and 20. This cam actuatingcoupling mechanism includes coupling pin which is mounted on main cam 78for longitudinal movement along a path parallel to and radially offsetfrom shaft 76. The trailing end of pin 140 extends into a clearance bore78c which opens into an annular well 78d formed in the rearward end ofthe cam 78. Within the well 78d there is mounted a face cam 142 whichhas a progressive annular rise arranged to drive coupling pin 140forwardly through well 78e at the forward end of cam 78 and into one oftwo diametricaly opposed coupling slots 48a, 48b formed on the adjacentface of carrier 48. Coupling pin 140 is biased against face cam 142 bybiasing spring 140a seated within clearance bore 780 and bearing againstcam 78 at one end and against a washer l40b pinned to coupling pin 140.When the bobbin transfer mechanism is in standby position A, thecoupling pin 140 is approximately at the 6 oclock position as seen inFIGS. 14 and 19 (position A being specifically designated in FIG. 19).In response to clockwise rotation of the main cam 78, as indicated bythe directional arrow in FIG. 19, coupling pin 140 moves along acircular path until it confronts the slot 480; and under bias of spring140a, it enters slot 48a and moves through a lost motion until thecoupling pin seats itself against the end of slot 48a. This occursapproximately at the 9 oclock position and corresponds to the transfermechanism 50 being in the retracted clearance position C. Continuedrotation of cam 78 and coupling pin 140 in the clockwise direction willcause carrier 48 to turn through 180, bringing coupling slot 48a intothe position occupied by coupling slot 48b in FIG. 19. Correspondingly,this brings coupling slot 48b into the position occupied by couplingslot 48a to thereby index the carrier 48 through 180. Thereupon, thedevelop ment of face cam 142 permits the coupling pin 140 to retractfrom coupling slot 48a to decouple carrier 48 from the actuating cam 78ain the indexed position until the next bobbin changing cycle. Decouplingoccurs at approximately position D on the cam development (see FIGS. 15and 16) such that the rise portion of cam track 78a will be operative toadvance the transfer member 52 relative to the indexed, but stationarycarrier in which a loaded bobbin case is presented for axial transferinto the bobbin holder and hook assembly 40. As the main cam 78completes the final portion of its rotation, corresponding to theloading of the bobbin case, the coupling pin 140 returns to the 9 oclockposition awaiting the next carrier indexing sequence which will occurduring the next bobbin changing cycle,but with coupling pin 140 enteringthe indexed coupling slot 48b.

Appropriate detent mechanisms may be provided, as is generallyunderstood by those skilled in the art, to releasably lock variouspartsof the mechanism in their respective indexed positions. For example, andas seen in FIG. 20, follower 52d on transfer member 52a may be providedwith a spring biased ball 52k engaged in one or the other of the ballrecesses on member 52a to successively lock member 52 in the rotationalposition wherein transverse pickup pin 52h is aligned with keyhole slot16 in bobbin case 94 and in the indexed rotational position in thelocked or pickup position relative thereto. In similar fashion, a detentmechanism may be associated with the carrier 48 to lock the same in oneor the other of its indexed positions wherein the successive loadedbobbin cases are presented in alignment with assembly 40 fortransferthereto- Mounted on carrier 48 are two thread runout sensors S1, S2associated respectively with bobbin case receivers R1, R2. The threadrunout sensors are disposed in succession in positions to bear againstthe bobbin case 94 on the base wall 102 contiguous to thread guide slot110 (as shown in FIGS. 2, 6 and 14) during the normal running mode ofthe sewing machine. However, during the bobbin changing cycle, therespective thread sensors S1, S2 must be retracted to a non-sensingposition relative to the holder 40c of assembly 40 to permit thewithdrawal of the empty bobbinv case and the replacement of the samewith the loaded bobbin case, followed by the return of the respectivesensors to the sensing position for the next running mode or stitchinginterval of the sewing machine. Since the construction of the respectivesensors S1, S2 and their movement between the sensing or operativeposition and the non-sensing or retracted position is the same, it willsuffice to describe only one of the sensors and its related mechanismsin detail. For example, as seen best in FIGS. 14 and 17 to 19; sensor S1includes a resilient contact blade 144 which is pivoted on carrier 48 atblade pivot 146 which extends parallel to and is spaced below thealigned hook shaft 42 and the transfer member 52. Blade pivot 46 isreceived within an insulating sleeve 148 and extends through carrier 48to the rearward face thereof (see FIG. 19) at which it carries a camfollower 150 which is biased by spring 152 anchored and insulated oncarrier 154 to normally pivot the contact blade 144 to the sensingposition. As previously indicated, the adjacent face of the main cam 78is provided with a well 78e which accommodates the rearward end of bladepivot 146 and the cam follower 150. The well 78e is surrounded by anannular flange 78f of the main cam 78 which is constructed of aninsulating material. As seen in FIG. 19, an annular segment of theelectricallyinsulating flange 78e is provided with a conductive insert156 which is disposed in the sector which confronts cam follower 150when the bobbin changing mechanism 44 is in its standby condition duringthe normal running mode of the sewing machine. The inner surface of theconductive insert 156 is provided with a cam cut- I out 156a whichpermits the cam follower 150 under influence of spring 152 to turn thecontact blade 144 of the corresponding sensor into its operative orsensing position. However, in response to rotation of the cam 78 in itsoperative clockwise direction (as shown in FIG. 19), the follower 150rides up onto the continuous peripheral camming surface afforded by thecylindrical surrounding wall of well 78e to turn the cam follower 150,blade shaft 146 and contact blade 144 into the retracted positionremoved from the assembly 40 and oriented to permit the unobstructivefunctioning of the bobbin changing mechanism during its functionalcycle.

While the main cam 78 is in its stationary starting po-' sition shown inFIGS. l4, l7 and 19 with the case transfer mechanism 50 in the standbyposition and the particular sensor blade 144 bearing against the bobbincase 94, provision is'made for completing the requisite connection fromthat blade to the control circuit shown in FIG. 6. This simply lightsbulb 560! over the secondary of transformer 560 to ground.56e when thebobbin thread runs out. However, in a more sophisticated circuit, thiscould initiate an automatic change cycle and disable the sewing machinefor the duration of that cycle. The circuit is completed by the mountingon front frame plate of an insulated brush 158 which is spring biasedagainst the outer periphery of conductive insert and also bears againstthe outer periphery of flange 78fduring rotation of main cam 78. Contactbrush 158 is connected by an appropriate lead wire 160 into thesimplified circuit shown in FIG. 6.

Provision is made on the indexab le carrier 48 and the stationary bobbinfeeding cartridge 54 for severing successive intermediate lengths ofthread (i.e., length bt2 in FIGS. 10 to 12) as the loaded bobbin case isindexed from the remote bobbin loading position to the case transferposition and to also guide the length of bobbin thread being drawnduring the indexing operation. In this illustrative embodiment, this isaccomplished by providing on the flat inner face 48d of carrier 48 acentral projecting thread guide flange 48c which is formed with acircumferentially extending V-shaped thread guide 48c (see FIG. 14).Accordingly, as the loaded bobbin case is indexed through its 180 travelrelative to the cartridge 54, the particular bobbin being indexed (i.e.,bobbin B2) is moving away from the next bobbin to be loaded (i.e.,bobbin B3) and the thread continuation 136 therebetween is lengthened,as by thread being drawn from the flat trailing face of bobbin B3.During this sequence, the lengthening thread continuation 136 extendswithin a portion the V-shaped thread guide 48c betwhen the 6 oclock and12 oclock positions. After drawout of the interconnecting length ofbobbin thread 136, cut-off is accomplished by mounting on the flatannular segment 48d of carrier 48 of movable cutters 162, 164 whichcooperate with a stationary cutter 166 which is mounted on the leadingend of magazine 54 in position to coact, in succession, with the movingcutter blades 162, 164. The successive coaction between cutter blades162, 164 with the stationary cutter 166 may be best appreciated byprogressively considering FIGS. 17 and 18. FIG. 17 shows cutter blade162 in its normal stationary and starting positions at the beginning ofa bobbin changing cycle, while FIG. 18 illustrates that cutter bladehaving turned counter-clockwise through approximately 180 to itsposition for cut-off of bobbin thread continuation bt2 drawn incident tothe advancement of bobbin B2 in case X2 toward the case transferposition in alignment with assembly 40. In this illustrative mechanismand as may be appreciated by considering FIG. 18, the cut-off of thethread continuation bt2 occurs, slightly in advance of the loaded bobbincase coming to rest in. the indexed case transfer position. Once cut-offis accomplished, the indexed bobbin case containing the loaded bobbin isfree to be loaded into the assembly 40 by the operation of the actuatingmechanism 50, as previously described.

A typical sequence of installation and operation will now be describedin order to facilitate a more complete understanding of the presentinvention:

In order to equip the sewing machine 30 with the bobbin changingmechanism 44 of the present invention, the usual slide plate of thesewing machine is removed and replaced with the slide plate 60 of thechassis 68 and is locked in position by tightening down of the mountingscrews 62. The otherwise conventional sewing machine is modified toreplace the conventional bobbin holder with the modified bobbin holder40c. The requisite supply of bobbins 134 is placed into the magazine 54,with the leading bobbin being biased into the aligned bobbin case whichis of the modified construction shown in FIGS. 7 to 9 inclusive. Theappropriate control is associated with the sewing machine 30. This mayrequire modification of the motor control if the more advanced versionof control is desired in which the sewing machine is disabled during thebobbin changing cycle and the cycle is automatically initiated inresponse to the runout of the bobbin supply in assembly 40. Finally, themechanism is placed into the illustrated mode for normal running of thesewing machine in which a loaded bobbin case is mounted within thebobbin holder 400 of assembly 40.

Thereupon, the sewing machine 30 is equipped for the completelyautomatic or semi-automatic change of bobbins, with the bobbin changebeing indicated by the lighting of signal light 56d. In thisillustrative embodiment, this is followed by the operator manuallymanipulating hand crank 42 to initiate and complete the bobbin changingcycle. At the end of the bobbin changing cycle, and with the bobbinthread coming underneath the sensor in the control illustrated in FIG.6, the signal light 56d is extinguished thereby advising the operatorthat the machine has been replenished with the requisite bobbin supplywhereupon the operator proceeds with the next stitching interval orsequence.

Since the stitching operation upon bobbin thread runout is detected witha length or tail of bobbin thread available beneath the fabric assembly(see FIG. 10), and in view of the operation of the bobbin changingmechanism, there is a high order of assurance that the stitch line willhave no discontinuities nor tell-tale evidence of bobbin runout and thesubsequent automatic replenishment. In its preferred form, the bobbinchanging mechanism is an attachment which may be easily installed on anysewing machine by simply replacing the otherwise conventional bobbinholder and employing the modified bobbin cases associated with themechanism. It will be appreciated, however, that the mechanism could beincorporated into the basic sewing machine design by the sewing machinemanufacturer as original equipment. Insofar as the bobbin supply is concerned, the illustrated and described supply is preferred in that thecoreless and cheekless bobbins of the described configuration facilitatea highly reliable change mechanism and cycle, and also maximize thebobbin thread supply for the particular bobbin case design.

What we claim is:

1. An automatic bobbin changing mechanism for a sewing machine of a typeutilizing a bobbin case containing a wound bobbin, a bobbin holder and arotating hook, said wound bobbin being received within a bobbin holderfor engagement of the bobbin thread by a hook rotating on a hook axiscomprising a support adapted to be mounted on said sewing machine, acarrier mounted on said support for rotation about a carrier axisextending parallel to and offset from said hook axis, said carrierincluding at least two bobbin case receivers at circumferentially spacedlocations and each adapted to receive a bobbin case for transfer betweena bobbin loading position at a removed location from said bobbin holderand a case transfer position at a confronting location in alignment withsaid bobbin holder, bobbin loading means at said removed locationadapted to receive a supply of coreless bobbins for feeding one of saidcoreless bobbins into an empty bobbin case in said bobbin loadingposition, means for indexing said carrier to bring the loaded bobbincase into said case transfer position, case transfer means movablerelative to said carrier and operable when the loaded bobbin case is insaid case transfer position to disengage the loaded bobbin case from itsreceiver and transfer the same into said bobbin holder of said sewingmachine, sensing means operable when said sewing machine is running todetect the runout of bobbin thread in the loaded bobbin case in saidsewing machine and means operable in response to said sensing means todisengage the empty bobbin case from said bobbin holder and return thesame to the receiver at said case transfer position for movement to saidbobbin loading position for reloading the empty bobbin case from saidsupply.

2. A mechanism according to claim 1 wherein said carrier includes tworeceivers circumferentially spaced at approximately 180 relative to eachother and said mechanism is operable with two bobbin cases which areloaded in succession and then transfer to and from said bobbin holderduring a bobbin changing phase of the mechanism cycle.

3. A mechanism according to claim 1 wherein said sensing means bearsagainst the loaded bobbin case while said sewing machine is running todetect the runout of the bobbin thread and including means for movingsaid sensing means to a retracted position prior to operation of themeans which disengages the empty bobbin case from said holder.

4. A mechanism according to claim 1 wherein the supply of bobbin isinterconnected by a length of bobbin thread and including means forcutting said length after loading the leading one of the bobbin into anempty bobbin case at said bobbin loading position.

5. A mechanism according to claim 4 wherein the means for cutting isoperable approximately at the time the loaded bobbin case moves intosaid case transfer position.

6. A mechanism according to claim 4 wherein the means for cuttingincludes a movable cutter for each bobbin case receiver and a stationarycutter coacting in succession with said movable cutters.

7. A mechanism according to claim 1 wherein said case transfer meansincludes a transfer member mounted for reciprocal movement along a pathin axial alignment with said hook axis and including first means forengaging an empty bobbin case in said bobbin holder and withdrawing thesame into an empty one of said case receivers on said carrier and secondmeans for thrusting a loaded bobbin case from a loaded one of said casereceivers into said bobbin holder.

8. A mechanism according to claim 7 wherein said case transfer member ismovable during its operating sequence through successive case receiversin said case transfer position and is retracted to a clearance positionrelative to said carrier during indexing thereof.

9. A mechanism according to claim 1 wherein said support is in the formof a slide plate adapted to replace the conventional slide plate of thesewing machine to suspend said mechanism in operative relation to saidbobbin holder.

10. An automatic bobbin changing mechanism for a sewing machine of thetype utilizing a bobbin case containing a wound bobbin, a bobbin holderand a rotating hook, said wound bobbin being received within a bobbinholder for engagement of the bobbin thread by a hook rotating on a hookaxis comprising a support adapted to be mounted on said sewing machine,a carrier mounted on said support for indexing movement, said carrierincluding at least two bobbin case receivers each adapted to receive abobbin case for transfer between a bobbin loading position at a removedlocation from said bobbin holder and a case transfer position at aconfronting location in alignment with said bobbin holder, bobbinloading means at said removed location adapted to receive a supply ofbobbins for feeding bob bins one at a time into empty bobbin cases insaid bobbin loading position, means for indexing said carrier to bringthe loaded bobbin case into said case transfer position and casetransfer means including a transfer member mounted for reciprocalmovement relative to said carrier and including first means for engagingan empty bobbin case in said bobbin holder and withdrawing the same intoan empty one of said case receivers on said carrier and second means forthrusting a loaded bobbin case from a loaded one of said case receiversinto said bobbin holder of said sewing machine.

11. A mechanism according to claim 10 including sensing means operableto detect the runout of the bobbin thread in the loaded bobbin case insaid sewing machine and means operable in response to said sensing meansto disengage the empty bobbin case from said bobbin holder and returnthe same to the receiver at said case transfer position for movement tosaid bobbin loading position for reloading the empty bobbin case fromsaid supply.

12. A mechanism according to claim 10 wherein said support is in theform of a slideplate adapted to replace the conventional slide plate ofthe sewing machine to suspend said mechanism in operative relation tosaid bobbin holder.

13. A mechanism according to claim 10 wherein said carrier includes tworeceivers circumferentially spaced at approximately relative to eachother and said mechanism is operable with two bobbin cases which areloaded in succession and then transfer to and from said bobbin holderduring a bobbin changing phase of the mechanism cycle.

14. A mechanism according to claim 11 wherein said sensing means bearsagainst the loaded bobbin case while said sewing machine is running todetect the runout of the bobbin thread and including means for movingsaid sensing means to a retracted position prior to operation of themeans which disengages the empty bobbin case from said holder.

15. A mechanism according to claim 10 wherein said case transfer memberis movable during its operating sequence through successive casereceivers in said case transfer position and is retractedto a clearanceposition relative tosaid carrier during indexing thereof.

1. An automatic bobbin changing mechanism for a sewing machine of a typeutilizing a bobbin case containing a wound bobbin, a bobbin holder and arotating hook, said wound bobbin being received within a bobbin holderfor engagement of the bobbin thread by a hook rotating on a hook axiscomprising a support adapted to be mounted on said sewing machine, acarrier mounted on said support for rotation about a carrier axisextending parallel to and offset from said hook axis, said carrierincluding at least two bobbin case receivers at circumferentially spacedlocations and each adapted to receive a bobbin case for transfer betweena bobbin loading position at a removed location from said bobbin holderand a case transfer position at a confronting location in alignment withsaid bobbin holder, bobbin loading means at said removed locationadapted to receive a supply of coreless bobbins for feeding one of saidcoreless bobbins into an empty bobbin case in said bobbin loadingposition, means for indexing said carrier to bring the loaded bobbincase into said case transfer position, case transfer means movablerelative to said carrier and operable when the loaded bobbin case is insaid case transfer position to disengage the loaded bobbin case from itsreceiver and transfer the same into said bobbin holder of said sewingmachine, sensing means operable when said sewing machine is running todetect the runout of bobbin thread in the loaded bobbin case in saidsewing machine and means operable in response to said sensing means todisengage the empty bobbin case from said bobbin holder and return thesame to the receiver at said case transfer position for movement to saidbobbin loading position for reloading the empty bobbin case from saidsupply.
 2. A mechanism according to claim 1 wherein said carrierincludes two receivers circumferentially spaced at approximately 180*relative to each other and said mechanism is operable with two bobbincases which are loaded in succession and then transfer to and from saidbobbin holder during a bobbin changing phase of the mechanism cycle. 3.A mechanism according to claim 1 wherein said sensing means bearsagainst the loaded bobbin case while said sewing machine is running todetect the runout of the bobbin thread and including means for movingsaid sensing means to a retracted position prior to operation of themeans which disengages the empty bobbin case from said holder.
 4. Amechanism according to claim 1 wherein the supply of bobbin isinterconnected by a length of bobbin thread and including means forcutting said length after loading the leading one of the bobbin into anempty bobbin case at said bobbin loading position.
 5. A mechanismaccording to claim 4 wherein the means for cutting is operableapproximately at the time the loaded bobbin case moves into said casetransfer position.
 6. A mechanism according to claim 4 wherein the meansfor cutting includes a movable cutter for each bobbin case receiver anda stationary cutter coacting in succession with said movable cutters. 7.A mechanism according to claim 1 wherein said case transfer meansincludes a transfer member mounted for reciprocal movement along a pathin axial alignment with said hook axis and including first means forengaging an empty bobbin case in said bobbin holder and withdrawing thesame into an empty one of said case receivers on said carrier and secondmeans for thrusting a loaded bobbin case from a loaded one of said casereceivers into said bobbin holder.
 8. A mechanism according to claim 7wherein said case transfer Member is movable during its operatingsequence through successive case receivers in said case transferposition and is retracted to a clearance position relative to saidcarrier during indexing thereof.
 9. A mechanism according to claim 1wherein said support is in the form of a slide plate adapted to replacethe conventional slide plate of the sewing machine to suspend saidmechanism in operative relation to said bobbin holder.
 10. An automaticbobbin changing mechanism for a sewing machine of the type utilizing abobbin case containing a wound bobbin, a bobbin holder and a rotatinghook, said wound bobbin being received within a bobbin holder forengagement of the bobbin thread by a hook rotating on a hook axiscomprising a support adapted to be mounted on said sewing machine, acarrier mounted on said support for indexing movement, said carrierincluding at least two bobbin case receivers each adapted to receive abobbin case for transfer between a bobbin loading position at a removedlocation from said bobbin holder and a case transfer position at aconfronting location in alignment with said bobbin holder, bobbinloading means at said removed location adapted to receive a supply ofbobbins for feeding bobbins one at a time into empty bobbin cases insaid bobbin loading position, means for indexing said carrier to bringthe loaded bobbin case into said case transfer position and casetransfer means including a transfer member mounted for reciprocalmovement relative to said carrier and including first means for engagingan empty bobbin case in said bobbin holder and withdrawing the same intoan empty one of said case receivers on said carrier and second means forthrusting a loaded bobbin case from a loaded one of said case receiversinto said bobbin holder of said sewing machine.
 11. A mechanismaccording to claim 10 including sensing means operable to detect therunout of the bobbin thread in the loaded bobbin case in said sewingmachine and means operable in response to said sensing means todisengage the empty bobbin case from said bobbin holder and return thesame to the receiver at said case transfer position for movement to saidbobbin loading position for reloading the empty bobbin case from saidsupply.
 12. A mechanism according to claim 10 wherein said support is inthe form of a slideplate adapted to replace the conventional slide plateof the sewing machine to suspend said mechanism in operative relation tosaid bobbin holder.
 13. A mechanism according to claim 10 wherein saidcarrier includes two receivers circumferentially spaced at approximately180* relative to each other and said mechanism is operable with twobobbin cases which are loaded in succession and then transfer to andfrom said bobbin holder during a bobbin changing phase of the mechanismcycle.
 14. A mechanism according to claim 11 wherein said sensing meansbears against the loaded bobbin case while said sewing machine isrunning to detect the runout of the bobbin thread and including meansfor moving said sensing means to a retracted position prior to operationof the means which disengages the empty bobbin case from said holder.15. A mechanism according to claim 10 wherein said case transfer memberis movable during its operating sequence through successive casereceivers in said case transfer position and is retracted to a clearanceposition relative to said carrier during indexing thereof.